I wrote a simple "RSS to Email" utility, which I use for reading feeds.

I can filter either in my mail-client, or in the utility itself, to include/exclude entries from feeds based upon regular expressions, and similar things.

It is pretty flexible - at least for the case when the feed itself contains the complete text of an entry. Often you'll find feeds contain only the "summary" of a blog-post, or article. Those are a bit harder to handle.